Load control devices may be used to control the amount of power delivered from an alternating current (AC) power source to an electrical load. An example of such a load control device is a wall-mounted dimmer.
FIG. 1 depicts a faceplate 10 and an actuator 12 of a prior art wall-mounted dimmer switch. The actuator 12 protrudes through an opening 14 in the faceplate 10, so as to be accessible to a user of the dimmer switch. The actuator 12 has an upper portion 16 and a lower portion 18. A user of the dimmer switch may adjust an amount of power the dimmer provides to a lighting load by sliding a finger along the upper portion 16 of the actuator 12. The user may switch the power to the lighting load on or off by touching the lower portion 18 of the actuator 12.
FIG. 2 depicts an exploded view of an example prior art wall-mounted dimmer switch 50 that may include a faceplate and an actuator, for example the faceplate 10 and the actuator 12 depicted in FIG. 1. The dimmer switch 50 includes a resistive touch pad 20 configured to be actuated by the actuator 12. The resistive touch pad 20 is configured to receive X and Y inputs from the actuator 12. The actuator 12 includes a plurality of legs 22 that are configured to make contact with the resistive touch pad 20. The legs 22 are spaced apart from each other along the actuator 12.
A user of the dimmer switch 50 may control an amount of power delivered to a lighting load by the dimmer switch by pressing a contact location on the actuator 12. As a user presses the actuator 12 at the contact location, the actuator 14 will cause one or more of the legs 22 to contact the resistive touch pad 20 at a corresponding contact location, for example a point having X and Y coordinates.
The contact location may provide an indication of a desired dimming level to be applied to the electrical load by the dimmer switch 50. The user may select a desired dimming level by pressing the actuator 12 at a contact location that corresponds to the desired dimming level. The dimmer switch 50 may include a controller that is configured to receive the contact location (e.g., X and Y coordinates) from the resistive touch pad 20. The dimmer switch 50 may translate the Y coordinate of the contact location into the desired dimming level and may use the X coordinate to determine if the actuator 12 is presently being actuated. The controller may cause a semiconductor switch of the dimmer switch 50 to deliver an amount of power to the lighting load that corresponds to the desired dimming level. An example of a dimmer switch, such as the dimmer switch 50 having the resistive touch pad 20, is described in greater detail in U.S. Pat. No. 8,173,920, issued May 8, 2012, entitled “Load Control Device Having A Modular Assembly,” the entire disclosure of which is hereby incorporated by reference.
The use of touch pad technology may be undesirably expensive. For example, resistive touch pads, such as the resistive touch pad 20, tend to be expensive because they are difficult to manufacture and include expensive materials, for example indium-tin oxide (ITO).